<html>
 <head>
  <link href="./leetcode-problem.css" rel="stylesheet" type="text/css">
 </head>
 <body>
  <div class="question_difficulty">
   难度：Medium
  </div>
  <div>
   <h1 class="question_title">
    24. Swap Nodes in Pairs
   </h1>
   <p>
    Given a&nbsp;linked list, swap every two adjacent nodes and return its head.
   </p>
   <p>
    You may
    <strong>
     not
    </strong>
    modify the values in the list's nodes, only nodes itself may be changed.
   </p>
   <p>
    &nbsp;
   </p>
   <p>
    <strong>
     Example:
    </strong>
   </p>
   <pre>
Given <code>1-&gt;2-&gt;3-&gt;4</code>, you should return the list as <code>2-&gt;1-&gt;4-&gt;3</code>.
</pre>
  </div>
  <div>
   <h1 class="question_title">
    24. 两两交换链表中的节点
   </h1>
   <p>
    给定一个链表，两两交换其中相邻的节点，并返回交换后的链表。
   </p>
   <p>
    <strong>
     你不能只是单纯的改变节点内部的值
    </strong>
    ，而是需要实际的进行节点交换。
   </p>
   <p>
    &nbsp;
   </p>
   <p>
    <strong>
     示例:
    </strong>
   </p>
   <pre>给定 <code>1-&gt;2-&gt;3-&gt;4</code>, 你应该返回 <code>2-&gt;1-&gt;4-&gt;3</code>.
</pre>
  </div>
 </body>
</html>